Pouring nozzle for continuous-casting machine

ABSTRACT

A method and nozzle construction for pouring liquid metal into a receiver, the width of which is several times greater than the thickness, for example, a continuous slab-casting mold. The metal discharges from a vessel supported above the receiver as a fanshaped stream broadened in the direction of the width of the receiver. As applied to casting slabs, the invention avoids localized high-temperature areas in the skin of a partially solidified casting as it emerges from the mold. The method and nozzle may also be used to advantage for pouring metal between the belts of a belt-type continuous-casting machine.

United States Patent Paul M. Auman;

James B. Wagstatf, both of Franklin Township, Westmoreland County, Pa.[21] Appl.No. 51,132

[22] Filed June 30, 1970 [45] Patented Jan. 11, 1972 [73] AssigneeUnited States Steel Corporation [72] Inventors [54] POURING NOZZLE FORCONTINUOUS-CASTING [56] References Cited UNITED STATES PATENTS 1,944,6111/1934 Reinartz et al 222/Foundry 2,826,793 3/1958 Flickinger,Sr.eta1ZZZ/Foundry Primary Examiner-Robert B. Reeves Assistant Examiner DavidA. Scherbel Att0rneyWa1ter P. Wood ABSTRACT: A method and nozzleconstruction for pouring liquid metal into a receiver, the width ofwhich is several times greater than the thickness, for example, acontinuous slabcasting mold. The metal discharges from a vesselsupported above the receiver as a fan-shaped stream broadened in thedirection of the width of the receiver. As applied to casting slabs, theinvention avoids localized high-temperature areas in the skin of apartially solidified casting as it emerges from the mold. The method andnozzle may also be used to advantage for pouring metal between the beltsof a belt-type continuouscasting machine,

E JAN] 1 m2 PATENT U SHEET 2 OF 2 3.633.654

INVE/V TORS.

PAUL M. AUMA/V and JAMES B. WAGSTAFF Attorney This invention relates toan improved method and nozzle construction for pouring liquid metal intoa receiver.

Although our invention is not thus limited, our method and nozzleconstruction are particularly useful for pouring liquid steel from atundish either into a continuous slab-casting mold or between the beltsof a belt-type continuous-casting machine, such as that shown inI-Iazelett US. Pat. No. 2,904,860 and other patents to the samepatentee. A typical continuously cast slab or strip has a width severaltimes its thickness. Conventional practice in continuously casting slabsis to pour one or more relatively coherent streams or jets of steelgenerally of a circular cross section from a tundish into an open-endedmold of appropriate cross section. If there is only one stream, it isdirected along the vertical centerline of the mold. If there are morethan one, they are spaced across a vertical plane which bisects the twoshorter sides of the mold. In either event the side faces of the castinghave localized areas adjacent each stream where the temperature isgreater than elsewhere. As the casting leaves the mold, only a thin skinat its outer surface has solidified; the core remains liquid for aconsiderable distance below the mold. This skin is easily ruptured,particularly along localized high-temperature areas adjacent thestreams. When a breakout of liquid metal occurs, it is usually in one ofthese areas. When a Strip is cast in a belttype casting machine, thereagain is a problem in distributing the liquid metal across the width ofthe belts.

An object of our invention is to provide an improved pouring method andnozzle construction which distribute liquid metal more effectivelyacross the width of a receiver, such as a mold or other casting machine,than previous methods or nozzle constructions.

A further object is to provide an improved pouring method and nozzleconstruction which produce a fan-shaped stream distributed across themajor portion of the width of a mold or belt-type casting machine.

In the drawing FIG. 1 is a partially diagrammatic side elevational view,partly in section, of a tundish and continuous slab-casting moldillustrating our pouring method;

FIG. 2 is a horizontal section on line Il-II of FIG. 1;

FIG. 3 is a top plan view ofour nozzle;

FIG. 4 is a vertical section on plane IVIV of FIG. 3;

FIG. 5 is a vertical section on plane V-V of FIG. 3;

FIG. 6 is a diagrammatic horizontal sectional view of a tundish andbelt-type continuous-casting machine illustrating our pouring methodapplied thereto; and

FIG. 7 is a diagrammatic vertical section on line VII-VII of FIG. 6.

FIGS. 1 and 2 show diagrammatically a conventional openended mold 10 forcontinuously casting steel slabs S. The mold has a width w several timesits thickness 2. A conventional tundish 12 is supported over the moldand is equipped with a nozzle 13 constructed in accordance with ourinvention and preferably with a slidable gate 14 for controlling flow ofmetal through the nozzle. The mold usually is of copper and it may beequipped with the usual liquid-cooling system, oscillating mechanism,liquid level control, etc. The tundish may be equipped with any suitablemechanism for supporting and operating its gate 14. We have not shownthese parts, since they are not involved in the present invention.

The nozzle 13 discharges a relatively thin fan-shaped stream M of liquidmetal into the mold 10, where it reaches a level L. This stream issymmetrical with respect to planes which bisect the mold in thedirection of its width w and its thickness t. The stream fans out in thedirection of the former plane and at its lower end occupies the majorportion of this plane. The partially solidified casting S emerges fromthe bottom of the mold.

FIGS. 3, 4 and 5 show nozzle 13 in detail. When the tundish 12 ispositioned for pouring, nozzle 13 is oriented with plane lV-IV of FIG. 3parallel with the width w of mold 10 and plane V-V parallel with thethickness 1. The nozzle is a cupshaped refractory body which has arelatively small circular pouring opening 15 in its bottom wall. Theupper surface of the bottom wall has a pair of relatively high areas 16at diametrically opposite sides of opening 15, which areas are bisectedby plane lV-IV. The upper surface of the bottom wall also has a pair ofrelatively low areas 17 at diametrically opposite sides of opening 15between the high areas, which 7 low areas are bisected by plane V-V. Theunder surface of the bottom wall has a recess 18 elongated beneath thehigh areas 15 and also bisected by plane IV-IV.

According to our pouring method, we support the tundish 12 over the mold10 with the nozzle 13 oriented as already described. We open the gate 14to pour liquid steel from the tundish into the mold. The configurationof the nozzle causes the stream issuing through its opening 15 to assumea fan shape broadened in the direction of the mold width w. The liquidmetal is distributed across almost the full width of the mold, and thereare are no localized high-temperature areas in the skin of the partiallysolidified casting S as it emerges from the mold. Thus the likelihood ofbreakouts or surface cracks is much diminished.

FIGS. 6 and 7 show our method and nozzle construction applied to pouringliquid metal between the belts 21 and 22 of a belt-typecontinuous-casting machine. The nozzle 13:: is mounted in the lowertransverse edge of a tiltable tundish 23 located to pour into the spacebetween belts, the opposed faces of which travel continuously in adownward direction. The nozzle is of similar construction to thatalready described, and its action in producing a fan-shaped stream issimilar. Such stream is distributed uniformly across the width of thebelts. Tilting of the tundish controls the volume and direction of flowthrough the nozzle.

Although we have described our invention as applied to pouring metalfrom a tundish into a continuous slab-casting mold, or a belt-typecontinuous-casting machine, it may have other application for pouringliquid from any bottom pour vessel into any receiver which has a widthsubstantially greater than its thickness.

We claim:

1. A nozzle comprising a cup-shaped refractory body having a circularpouring opening in its bottom wall, the upper surface of the bottom wallhaving a pair of relatively high areas at diametrically opposite sidesof said opening and a pair of relatively low areas at diametricallyopposite sides of said opening between said high areas, the undersurface of the bottom wall having a recess elongated beneath said highareas, whereby liquid discharging through said opening forms afan-shaped stream broadened in the direction of elongation of saidrecess.

2. A bottom pour vessel equipped with a nozzle constructed as defined inclaim 1.

3. A vessel equipped with a nozzle constructed as defined in claim 1located in a lower transverse edge thereof.

4. In combination, a continuous slab-casting mold having a widthsubstantially greater than its thickness, a tundish supported over saidmold, said tundish having in its bottom wall a nozzle constructed asdefined in claim 1 oriented so that the fan-shaped stream dischargingtherefrom is symmetrical with respect to planes which bisect the mold inthe direction of its width and its thickness and broadened in thedirection of the first-named plane to distribute steel across the moldwidth, whereby localized high-temperature areas are avoided in the skinof a partially solidified casting emerging from said mold.

5. In combination, a belt-type continuous-casting machine which includesa pair of spaced-apart belts, opposed faces of which travel in adownward direction, and a tiltable tundish for pouring liquid metal intothe space between said belts, said tundish having a nozzle constructedas defined in claim 1 in its lower edge adjacent the space between beltsfor discharging a fan-shaped stream of metal into said space, saidstream being broadened in the direction of the width of the belts.

1. A nozzle comprising a cup-shaped refractory body having a circularpouring opening in its bottom wall, the upper surface of the bottom wallhaving a pair of relatively high areas at diametrically opposite sidesof said opening and a pair of relatively low areas at diametricallyopposite sides of said opening between said high areas, the undersurface of the Bottom wall having a recess elongated beneath said highareas, whereby liquid discharging through said opening forms afan-shaped stream broadened in the direction of elongation of saidrecess.
 2. A bottom pour vessel equipped with a nozzle constructed asdefined in claim
 1. 3. A vessel equipped with a nozzle constructed asdefined in claim 1 located in a lower transverse edge thereof.
 4. Incombination, a continuous slab-casting mold having a width substantiallygreater than its thickness, a tundish supported over said mold, saidtundish having in its bottom wall a nozzle constructed as defined inclaim 1 oriented so that the fan-shaped stream discharging therefrom issymmetrical with respect to planes which bisect the mold in thedirection of its width and its thickness and broadened in the directionof the first-named plane to distribute steel across the mold width,whereby localized high-temperature areas are avoided in the skin of apartially solidified casting emerging from said mold.
 5. In combination,a belt-type continuous-casting machine which includes a pair ofspaced-apart belts, opposed faces of which travel in a downwarddirection, and a tiltable tundish for pouring liquid metal into thespace between said belts, said tundish having a nozzle constructed asdefined in claim 1 in its lower edge adjacent the space between beltsfor discharging a fan-shaped stream of metal into said space, saidstream being broadened in the direction of the width of the belts.